The apparatuses with a function of power saving are described in various documents, for example, in Japanese Patent Laid-Open No. 2005-267100, Japanese Patent Laid-Open No. 2005-267097, and Japanese Patent Laid-Open No. 2005-269013. Japanese Patent Laid-Open No. 2005-267100 discloses an image forming apparatus that enters into a power saving mode when a certain period of time passes after a job is finished, when an instruction is given from a host PC connected to a network, or when an input is given with an operation panel.